Adjustable height ramp structures, for elevating the wheel of a vehicle, are shown by U.S. Pat. No. 1,922,551, granted Aug. 15, 1933, to Marshall K. McCosh; U.S. Pat. No. 2,675,210, granted Apr. 13, 1954, to Ernest E. Lowber; U.S. Pat. No. 3,295,829, granted Jan. 3, 1967 to Charles H. Tarr and U.S. Pat. No. 4,165,862, granted Aug. 28, 1979, to Steven A. Bennett.